stress test problem: amp not outputting sound. Re-plugging the input fixes this

[sep]

I've set up an installation with my company where the computer outputs sound through a 6ch audio interface into three 2ch audio switches into three 2ch amps into 6 speakers. The computer gets reset often while the amps remain on. Sometimes, there is no sound from one of the amps (speaker pairs) after a computer restart. This is fixed by doing one of the following:

1) Turning the amp off and on or unplugging and replugging its power

2) unplugging and replugging cables between the interface and the amp

I'm going to go to the venue soon to run some more tests and try and isolate the problem better... any ideas for what it could be? I thought it was just the amp, but according to an on-site co-worker, this happened at least once with another amp model...

 

[AnalogSteph]

That is... peculiar.

My first thought would be a spuriously triggered DC protection, but that wouldn't explain why #2 fixes it. I suspect the issue may be somewhere at the very amplifier output or in the speaker cabling, so checking the whole run for intermittent / poor contact may be advisable. Is it always the same speaker pair?

 

[mansr]

There's something you're not telling us. Two of the 6 channels on that interface are digital.

 

[sep]

There's something you're not telling us. Two of the 6 channels on that interface are digital.

Yes, for channels 5&6 we're using this adapter. @AnalogSteph Sometimes the problem affects pairs 1&2 and 3&4 though, which don't use the DAC.

 

[sep]

We're thinking of testing it with a different audio interface, the MOTU MK3 Lite Hybrid, which doesn't require the DAC. We're also planning on replacing the Little Bear audio switches with Behringer Mini-Mixers. Here's the plan for that. If you see any problems, let me know! The main suspects are the audio interface, the amps and the software (TouchDesigner, using the interface's ASIO driver), but we're going to run some thorough tests to narrow down what it is.

 

[restorer-john]

The whole setup sounds like a complete balls-up disaster to me for a company installation.

Why one earth not go for proper pro gear, multichannel digital input amps and proper distribution, mixing and switching? This Aliexpress special pile of disparate stuff needs to go.

 

[sep]

The whole setup sounds like a complete balls-up disaster to me for a company installation.

Why one earth not go for proper pro gear, multichannel digital input amps and proper distribution, mixing and switching? This Aliexpress special pile of disparate stuff needs to go.

Hey, thanks for your reply. Yeah, we got three cheap stereo amps which I'm sure have been one of the problems from the start, just because doing so was way less expensive than getting one amp that outputs 6 channels. Can I ask for some recommendations?

amps & interface:
Why is a digital input amp superior and can you recommend some? The interface we've been using has analog outputs for channels 1-4 and then digital (spdif) for 5-6 (the interface in the diagram would have analog outputs for all channels). Would a special audio interface be required that only outputs digital signals, and what models/makers would you recommend?

distribution, mixing and switching:
Do you mean we should use a single large mixer to handle signal duplication and routing for all 9 input and 6 outputs channels (instead of the two HM-4 and three Behringer Mini-Mixers)? What device would you recommend for that? It seems like it's hard to find mixers that would do that, or that they'd be very expensive and large.

I guess the point of the digital inputs is to package more inputs together and cut down on the amount of cables? To clarify, the inputs are

6 channel from the computer
2 channel from a tablet-like device
1 channel from a wireless mic receiver (1/4")

The 2 channel and 1 channel inputs need to be sent to all 6 speakers. First time doing something like this so really happy for any advice.